A role of the heavy subfraction of the floating lipids in acute alcoholic fatty liver of rats.

Two subfractions of floating lipids were studied to clarify the subcellular pathogenesis of ethanol-induced acute fatty liver in the rat. The main lipid in both the heavy and light subfraction was triglyceride, but the heavy subfraction was richer in phospholipids than the light subfraction. After ethanol-treatment of the animals, not only triglyceride but also phospholipids increased significantly in the light subfraction. The similarity of the phospholipid species in the two subfractions suggests a possible exchange of lipids between them. The heavy subfraction consisted of membrane-free lipid droplets of very low density lipoprotein (VLDL) size plus membrane-bound, vacuolated organelles; the light subfraction consisted of membrane-free lipid globules larger than 1000 nm in diameter. Occasionally adherent particles, 40 to 100 nm in diameter, were detected on the surface of the lipid globules. After ethanol treatment, the ratio of adherent particles to lipid globules increased significantly. These observations suggest that the biogenesis of acute alcoholic fatty liver in rats involves first the formation of membrane-free lipoproteins of VLDL size in the cytoplasm and subsequently their fusion to pre-existing lipid globules.     

大鼠慢性酒精性脂肪肝造模方法的改进

目的用一种简单可行且与临床接近的方法建立大鼠慢性酒精性脂肪肝模型。方法将66只健康雄性SD大鼠随机分成正常对照组、白糖组、模型组3组。正常对照组大鼠自由饮水;白糖组大鼠自由饮用含10%的糖水;模型组大鼠自由饮用55°二锅头白酒配制成不同浓度的酒水饮料,并含有10%的白糖,其白酒度按照5%、10%、15%、20%、25%、30%、35%、40%（V/V）逐渐递增,每个浓度持续10 d,40%时维持20周。并于第15、20、25周末随机取2只模型组大鼠行肝脏病理切片观察,造模结束后测定各组血清谷丙转氨酶（ALT）、谷草转氨酶（AST）及血脂四项指标即甘油三酯（TG）、总胆固醇（CHO）、高密度脂蛋白胆固醇（HDLC）、低密度脂蛋白胆固醇（LDLC）水平并观察肝脏病理形态学改变。结果随着造模时间延长,模型组肝脏脂肪变性程度逐渐加重,造模结束后肝脏病理提示为重度脂肪变性,血清转氨酶及血脂（TG、CHO、LDLC）水平明显升高,与正常对照组比较差异有统计学意义（ALT：P〈0.01,AST、TG、CHO、LDLC：P〈0.001）,HDLC水平降低,与正常对照组比较差异有统计学意义（P〈0.001）。结论本造模方法与人类慢性酒精性脂肪肝的发生发展相似,并且简单易行,稳定,可重复,动物死亡率低,为慢性酒精性脂肪肝的相关研究提供了较有价值的动物模型。     

Emerging role of redox dysregulation in alcoholic and nonalcoholic fatty liver disease

Fatty liver disease (FLD), associated with chronic alcohol consumption or obesity, is a serious medical problem. Strong evidence indicates that oxidative stress and dysregulation of redox-sensitive signaling pathways are central to the pathobiology of FLD. Herein, this Forum summarizes current knowledge regarding mechanisms of FLD from both clinical and experimental studies. Special emphasis is given to the role of redox biology disturbances in the initiation and progression of FLD from both chronic alcohol consumption and obesity. Focus areas in this Forum include discussions on the (i) multi-hit hypothesis; (ii) interaction of adipokines and redox signaling pathways; (iii) role of sub-cellular organelle systems (i.e., endoplasmic reticulum and mitochondria); and (iv) contribution of the innate immune system, in FLD. A state-of-the-art discussion is also included highlighting key lessons learned from experimental studies using rodent models of FLD.     

Electron microscopic study on the floating lipids of human liver. Lysosomal involvement in the fatty liver associated with diabetes mellitus

Using fractionation, subcellular pathogenesis of the fatty liver was investigated. Floating lipids were isolated from a small amount of the liver obtained by needle biopsy. The volume of the floating lipids was correlated to the grading of fat infiltration of the intact tissue. Of lipid-rich particles bound by membranous structures, the volume of lipolysosomes in the patients with liver damage associated with diabetes mellitus was greater than that of alcoholics. Hypercholesterolemia was another feature characteristic of the liver disease exhibiting lipolysosome proliferation. These observations suggest a lysosomal involvement in fatty degeneration of the liver in diabetics through an overload of cholesterol.     

Serum lipids and total fatty acids in chronic alcoholic liver disease at different stages of cell damage

Summary Lipid classes and per cent composition of total fatty acids were investigated in serum of normal subjects and patients with chronic alcoholic liver disease. In view of the histological findings, the latter were classified in 5 groups according to the severity of their liver damage.A correlation was shown between changes in lipid classes with morphological liver abnormalities, whilst a similar correlation could not be established with alterations of total fatty acids per cent composition.

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Zusammenfassung Es wurden die Lipidklassen und die Perzentsätze von Gesamtfettsäuren an Serum von normalen sowie chronischen alkoholischen leberkranken Menschen untersucht, die aufgrund der histologischen Befunde in 5 Gruppen je nach dem Schweregrad der Leberschädigung unterteilt worden waren.Es hat sich gezeigt, daß eine Korrelation zwischen den Veränderungen der Lipidklassen und den morphologischen Leberveränderungen besteht. Im Gegensatz dazu war keine ähnliche Korrelation zwischen den Perzentsatzveränderungen der Gesamtfettsäuren festzustellen.

     

Ultrastructural detection of cholesterol in the liver of alcoholic rats

Central Research Institute of Gastroenterology, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 5, pp. 510–512, May, 1990.     

Histopathological diagnosis of non-alcoholic and alcoholic fatty liver disease

The diagnostic procedures in patients with suspected fatty liver disease-with or without known alcohol consumption-should be standardized and generally accepted. We therefore present a guideline, summarizing the current concepts of etiology, diagnostic as well as differential diagnostic of patients with fatty liver disease. Alcoholic as well as and non-alcoholic fatty liver are characterised by lipid deposition in hepatocytes. The diagnosis of steatosis is made when lipid deposition exceeds 5% of hepatocytes, while involvement of more than 50% is called "fatty liver". An additional inflammatory reaction leads to alcoholic (ASH) or non-alcoholic steatohepatitis (NASH). Steatohepatitis is present when both inflammatory infiltrates of mixed cells in the small liver lobules as well as liver cell injury in terms of ballooning can be detected. Liver biopsy represents the "golden standard" for confirming diagnosis and determining inflammatory activity and potential fibrosis of fatty liver disease. The differential diagnosis of ASH vs. NASH cannot be made on the basis of histological criteria alone. Steatosis, inflammatory changes and hepatocytic injury can be semiquantified as a "Brunt Score" or "NAS" (NAFLD activity score), providing the basis on which to decide whether or not steatohepatitis is present. People at increased risk of developing a fatty liver possess an increased risk of developing chemotherapy-associated steatohepatitis. Histologically, pediatric NASH differs from adult NASH and is often only clinically manifest through a mild if persistent elevation in transaminases.     

Is malnutrition necessary for the development of alcoholic fatty liver in the rat?

Ingestion of various liquid diets containing 36% calories as ethanol and 35% calories as fat does not provide adequate nutrition to young growing rats. Studies conducted with the aforementioned diets have the effects of malnutrition confounded with those of alcohol administration. Feeding a 26% alcohol liquid diet, which results in adequate nutrient intake with the same level of alcohol ingestion as the 36% alcohol diet, does not result in fatty liver development in the rat. The concept that prevailed for 25 years that fatty liver is caused despite adequate nutrition and hence is due to alcohol alone is therefore erroneous.     

Mitochondrial genome architecture in non‐alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) is associated with mitochondrial dysfunction, a decreased liver mitochondrial DNA (mtDNA) content, and impaired energy metabolism. To understand the clinical implications of mtDNA diversity in the biology of NAFLD, we applied deep‐coverage whole sequencing of the liver mitochondrial genomes. We used a multistage study design, including a discovery phase, a phenotype‐oriented study to assess the mutational burden in patients with steatohepatitis at different stages of liver fibrosis, and a replication study to validate findings in loci of interest. We also assessed the potential protein‐level impact of the observed mutations. To determine whether the observed changes are tissue‐specific, we compared the liver and the corresponding peripheral blood entire mitochondrial genomes. The nuclear genes POLG and POLG2 (mitochondrial DNA polymerase‐γ) were also sequenced. We observed that the liver mtDNA of patients with NAFLD harbours complex genomes with a significantly higher mutational (1.28‐fold) rate and degree of heteroplasmy than in controls. The analysis of liver mitochondrial genomes of patients with different degrees of fibrosis revealed that the disease severity is associated with an overall 1.4‐fold increase in mutation rate, including mutations in genes of the oxidative phosphorylation (OXPHOS) chain. Significant differences in gene and protein expression patterns were observed in association with the cumulative number of OXPHOS polymorphic sites. We observed a high degree of homology (～98%) between the blood and liver mitochondrial genomes. A missense POLG p.Gln1236His variant was associated with liver mtDNA copy number. In conclusion, we have demonstrated that OXPHOS genes contain the highest number of hotspot positions associated with a more severe phenotype. The variability of the mitochondrial genomes probably originates from a common germline source; hence, it may explain a fraction of the ‘missing heritability’ of NAFLD. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Histochemical investigation of the proteins of the rat liver in acute alcoholic intoxication

Summary A histochemical study was made of the effect produced by acute alcoholic intoxication on proteins in the liver of rats. For this purpose 50° ethyl alcohol (1.2 ml of absolute alcohol per 100 g the animal's body weight), was introduced through a stomach tube. The animals were, sacrificed in 1,4, 24 h and 5, 8, 12 days. The rats given the corresponding amount of water served as control. Sections were treated by Danielli's method with the use of tetrazone compound.Following the 4th h after the alcohol administration the amount, of proteins was progressively decreasing, while the hepatic cell cytoplasm became vacuolized; there was a rise in the nuclear protein content attended by an enlargement of nuclei as well as by an increase in the amount and size of nucleoli. The mentioned changes attained the peak 24–28 h following the alcohol intake. Later, the protein components of hepatic cells weee gradually restoring, this being attended by an enhanced mitotic activity; the restoration was completed by the 8th–14th day. Possible mechanisms governing disturbance of the hepatic protein metabolism under the effect of alcohol are discussed.Presented by S. A. Sarkisov, Active Member, Academy of Medical Sciences, USSR Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 58, No. 10, pp. 37–41, October, 1964     

Pathologic changes in the cytokeratin pericanalicular sheath in experimental cholestasis and alcoholic fatty liver

The architectural framework of the pericanalicular sheath composed of cytokeratin intermediate filaments (IFs) was examined after phalloidin treatment, bile duct ligation, and alcoholic fatty liver in rats to assess the role of IFs in experimental cholestasis. Electron microscopy examination of whole mount unembedded extracted liver slices was employed to visualize the cytoskeleton. Immunofluorescence staining and immunoelectron microscopy of the sheath were also performed using monoclonal antibodies to rat hepatocyte cytokeratins CK49 and CK55. The thickness of the wall and the diameter of the lumens were measured. In the phalloidin-treated rats, the pericanalicular sheath was markedly dilated and thickened. Immunofluorescence staining showed that the CK49 and CK55 IFs were localized in the pericanalicular region, particularly in the pericentral area. Immunoelectron microscopy documented that the IFs at the thickened pericanalicular sheath consisted of both CK49 and CK55, which means that the thickening of the bile canaliculus was in part due to an increase of IFs and not just due to an increase in actin filaments. In the livers where the bile duct was ligated, the pericanalicular sheath was irregularly dilated and some parts of the sheath appeared thinned out or missing. The belt desmosome also appeared absent focally in the pericanalicular sheath. Immunofluorescence studies showed that the staining for CK49 and CK55 was reduced focally in the pericanalicular region. The CK55 antibody stained the cytoplasm of hepatocytes in the periportal area more intensely when compared with the controls. These results indicated that the pericanalicular sheath and the belt desmosome were focally disrupted in response to extrahepatic bile duct obstruction. In the ethanol-fed rats, the pericanalicular sheath was dilated, thickened and tortuous, and appeared focally flattened by large fat droplets. IFs in the cytoplasm were pushed to the cell periphery and were compressed against each other by the fat droplets. CK55 and CK49 appeared increased as indicated by the observed immunofluorescence at the pericanalicular region. Immunoelectron microscopy showed that IFs of the thickened pericanalicular sheath were composed of CK55 and CK49. It is suggested that the pericanalicular sheath functions to mechanically provide a scaffolding for the bile canaliculus which is vulnerable to the different forces involved in cholestasis of different pathogenesis such as focal compression and distortion by fat, hypertrophy in response to increased F actin and focal destruction by increased intracanalicular pressure.